Filamentary reinforcement for laminated articles and related methods



Feb. 18, 1969 SCI-IAFER 3,428,518

- FILAMENTARY REINFORCEMENT FOR'LAMINATED ARTICLES AND RELATED METHODS Filed Jan. 24. 1963 IN VEN TOR.

lfE/V/V'i'l/ 4. 5094f??? BY/Q/ The preform is subjected to tearing and distortion in the storage and handling between the instant it leaves the pre- United States Patent 'ice Feffl fiil g interstices of the mat. Upon application of curing heat to 3,428,518 the mold, the liquid resinous composition is cured while FILAMENTARY REINFORCEMENT FOR LAMI- the preform mat is disposed under compression within the NATED ARTICLES AND RELQTED METHODS mold cavity. After the cure has been effected, the mold Kenneth schafel': Cedarburg, asslgnor to Free cavity is opened and a laminated article is removed which man Chemical Corporation, Port Washington, Wis., 21

contains cured thermoset resi ou aterial havin fibrous corporation of Delaware h S m S g Filed Jam 24' 1963, sen No. 253545 reinforcing materials randomly dispersed throughout its U.S. Cl. 161-170 13 Claims y- I t, CL C03c 2 5 /02 In transfer molding, the preform mat is placed in a mold cavity which is then closed. Fluid resin is forced into the This invention relates to resin-coated fibers and to a closed mold cavity under pressure and cured. method for making the same; to laminating preform mats Where preform mats are not employed, it is feasible to made from such resin-coated fibers and to a method for introduce reinforcing fibers and liquid thermosetting resins making the same; and to a method for making laminated directly into a mold cavity and allow the fibers to become articles from such resin-coated fibers. randomly oriented as the mold cavity is closed. The tech- The invention has its utility in the general field of fibernique is applied in both compression molding and transfer reinforced thermoset plastic laminated articles. molding.

Glass reinforcing fibers frequently are coated with vari- Y PRIOR ART ous reagents for promoting the wetting of their surfaces Laminated articles are manufactured from thermowith the liquid thermosetting resinous solutions, and to setting resinous substances and fibrous reinforcing mateimprove th b d b t th resin d th fib r rials. The thermosetting resinous substances frequently comprise unsaturated polyester resin compositions which THE PRESENT INVENTION normally are liquid solutions of alpha-beta ethylenically I unsaturatedpolyesters contained in a liquid copolymer- ACCOFdlIlg t0 the Present lhvehhoh, lhdlvldllal glass izable monomer such as styrene. The fibrous reinforcing fibers are coated With a y thefmosettihg resinous C0111- materials most commonly employed are glass fibers. P P h h n he curefi directly Without the use Of The glass fibers are commercially available in theform addltlohal hq collolylhhrlzable mohomefs- The thermoof roving which customarily comprises a grouping of about Sethhg heslhous P PP moreover, can h Partially 6 0 strands of glass fibers. The individual strands of the h wlthoht f f 1h Ofdfil to serve a blhder for f reving customarily comprise 02 or 204 individual fila. taming the lndivldualfibers of the lammating preform 1n ments of glass. The typical roving thus comprises 6,120 random ol'lehtatloh- 12,240 individual glass fib Ifreferably the dry thermosetting resinous composition To form laminating preform mats, a length of roving is whlch 15 pp to the ihdlviihlal fibers: as a Coating introduced into a chopping machine which cuts the roving P a IhlXture 0f the fOHOWlIlg mammals: into relatively short lengths (2-3 inches is common) of an unsaturated Polyester resin having alpha-beta individual fibers. The short lengths of individual fibers are ethylenic unsaturation; and directed as an airborne stream against a preform screen (b) a diester-polyether having two terminal C=CH which 'has a configuration corresponding to the shape of groups and having the structural formula p O 0112: ooomonomcH-C}o@oornenorno-nQo@oomonomot:0:011,

, R 011 a l OH i 6H it I a H3)? (CH3): the ultimate article which is to be laminated. customarily whereinR is selected from the class consisting of hydroa reduced pressure is maintained behind the screen in gen, lower aliphatic hydrocarbon radicals and phenyl radiorder that the glass fibers will be retained on the surface cals; and n is an integer from zero to twelve. These matein a substantially uniform thickness. rials can be fabricated by reacting acrylic acid, methacrylic While the fibers are thus retained on the-preform screen, acid or cinnamic acid with an epoxy resin having the a suitable liquid adhesive'is sprayed over the preform mat formula Y O Y 0 CHZGHCH o C. OOH CHCH O-L. 0 OOH CHCH;

a in l a)2 (CH vto retain the glass fibers in their randomly oriented rela- Alternatively the materials may be fabricated by reacting tion. Customary adhesives are water emulsion of p0ly- 'glycidylacrylate, glycidyl methacrylate or glycidyl cinesters, polystyrene, urea-formaldehyde, starch, acrylic adnamate i h bi h 1-A h n i -hesives, and thelike. After the adhesive has dried (usually Alternatively h diest upolyether (b) may be i i :heat isapplied), the preform mat is removed fr0 m the P alone, without the unsaturated polyester resin as the coatform screen and stored for later use in lammating molds. composition The unsaturated polyesters are fabricated by reaction of glycols such as ethylene glycol, propylene glycol, and the like with dicarboxylic acids, at least a portion of which comprise alpha-beta-ethylenically unsaturated'dicarboxylic acids or anhydrides such as maleic acid, fumaric acid,

laminating mold."

In compression molding, the preformmat is introduced =into'a laminating mold which has a shape corresponding form screen and the moment when it is positioned in a to that of the desired laminated article. A liquid thermomalelc h s and like- The usual unsaturated setting resinous composition, usually a styrene solution of P lyester 1s a solld S bs of an extremely Viscous unsaturated polyesters is introduced into the mold cavity. y p at room t p The mold is closed and, under pressure, the resin sur- The diester polyethers are usually solid ubstances at rounds the glass fibers of the preform mat and fills the room temperature, although where the value of n in the structural formula is zero, the materials may be a viscous s rup.

A mixture of the described diester polyether and the unsaturated polyester will copolymerize to yield a thermoset resinous substance. The use of polymerization initiators such as benzoyl peroxide, dicumyl peroxide and similar peroxy compounds will accelerate the thermoset curing of the mixtures. The described diester-polyether will homopolymerize with itself.

The specific unsaturated polyester and the specific diester polyether are selected to provide a mixture which is a dry solid substance at ambient room temperatures. Where a syrupy unsaturated polyester is selected, the diester diether should be a solid substance. Where both the unsaturated polyester and the diester diether are solids, there is no difliculty. Where the diester polyether is syrupy, the unsaturated polyester should be a solid substance. Suitable fillers may be included with the resins to increase the dryness of the resinous composition. Polyvinyl formal may be added to increase dryness of the resinous composition.

To apply the present polymerizable composition to the fibers, the materials are dissolved in a suitable inert solvent such as acetone, methyl-ethyl-ketone, xylene, benzene and the like. The quantity of solvent is determined by the thickness of coating which is desired on the fibers. In general, as the viscosity of the solvent solution of the resinous composition increases, the thickness of the resin coating will increase. The bath is maintained at a temperature well below that at which polymerization occurs. Room temperature baths are suitable.

The individual fibers or strands of fibers are passed through the solvent bath containing the resin mixture and are separately withdrawn with a coating of the resinous mixture solution thereon. The solvent is flashed from the coated fibers or strands leaving behind dry-coated fibers. The dry-coated fibers may be utilized as such, but preferably they are combined into a strand or roving containing individual coated fibers or strands. The roving or strands thus contain fibers which are individually coated with a dry, thermosetting resinous composition. They may be chopped into short lengths in accordance with the prior art of fabricating laminating preform mats. However, the present preform mats do not require extrinsic adhesive sprays for setting. While it is permissable to utilize a suitable adhesive spray to set the preform mat, it is preferred to heat the preform mat slightly while it is yet retained on the preform screen to cause slight fusion of the thermostat resinous coating of the fibers. The fusion will occur at points of fiber-to-fiber contact. Cooling of the fused coating will restore hardness and dryness so that the resulting preform mats may be removed from the preform screen and handled with significantly less tearing and damage in storage and movement. The slight heating of the preform mats should be carefully regulated to avoid initiation of copolymerization. Temperatures of about 100-250 F. should suifice.

The resulting laminating preform mats may be introduced into a laminating molding cavity and compressed therein. No additional liquid copolymerizable monomers are required to effect a complete cure of the present preform mats, since they will contain the precise quantity of thermosetting laminating resins for completing the desired laminates. Of course, if additional liquid copolymerizable monomers are desired in the molding cavity, they may be added without departing from the spirit of the invention. However, in the preferred embodiment of the laminating molding process, no additional monomers are employed. The entire laminating process is dry.

After the molding cavity has been closed and the present preform mat has been compressed therein, application of heat will cause the resinous coating to fuse and fill the interstices of the fibrous preform mat. Thereafter the thermosetting polymerization reactions proceed to C0111- 4 pletion. Typical curing temperatures are in the range of 100-375 F.

The thickness of the resin coating on the fibers should be such that the resulting coated fibers contain from 20 to percent fiber by weight. The structural properties desired in the resulting laminated article will in large measure determine the proper ratio of fiber to resin and hence the thickness of the resin coating.

The resin bath desirably will contain both an inhibitor of polymerization (such as quinone, hydroquinone, toluhydroquinone, tertiary butyl catechol, and the like) in an amount from 0.1 to 2.0 percent by weight of the resin. The resin bath further may contain a suitable polymerization initiator (such as cumene hydroperoxide, benzoyl peroxide and the like) in an amount from about 0.1 to 2.0 percent of the weight of resin.

The objects of the present invention include:

To provide fibers coated with a dry, thermosetting resinous composition;

To provide a method for making fibers with a dry, thermosetting resinous composition;

To provide laminating preform mats from fibers having a coating of dry, thermosetting resinous substances;

To provide laminating preform mats wherein the fibers are retained in their random orientation through fusion of a thermosetting resinous coating substance covering each individual fiber;

To provide a method for preparing preform mats from fibers coated with a dry, thermosetting resinous substance wherein the coating serves to retain the random orientation of the fibers through fusion with itself at points of fiber-tofiber contact within the preform mat;

To provide a method for making laminated articles from fibers which are coated with a dry, thermosetting resinous composition without the need for additional liquid copolymerizable monomers.

These and other objects and advantages of the present invention will become apparent from the following detailed description by reference to the accompanying drawings in which:

FIGURE 1 is a perspective illustration of a fiber coating bath, drier and spool;

FIGURE 2 is a perspective illustration of a spool of coated fibrous strands, a chopping device and a preform screen;

FIGURE 3 is cross section illustration of a two-piece laminating mold in an open position with a laminating preform positioned within the molding cavity; and

FIGURE 4 is a cross sectional illustration of the laminating mold of FIGURE 3 in the closed position with the laminating preform mat compressed.

Referring to FIGURE 1 there is illustrated in schematic perspective a resin coating bath which consists of a tank 10 filled with a solvent bath 11 containing thermosetting resinous composition. The resinous composition includes the described diester-polyethers and preferably includes also an unsaturated polyester having alpha-betaethylenic unsaturation. The tank 10 has suitably located rollers 12 which direct fibers 13 into the solvent bath 11 and out of the solvent bath 11. The individual fibers 13 are preferably individually coated and withdrawn from the solvent bath 11 through a solvent removal zone 14 wherein the solvent is flashed from the coated fibers. Dry coated fibers emanate from the solvent removal zone 14 and are collected into strands 15 for spooling on a suitable spool 16. Instead of coating individual fibers, groups or strands of fibers may be coated as an entity and collected into larger strands for spooling.

The strands 15 thus contain a plurality of individual discrete fibers, each of which has a dry coating of the present resinous composition. The strands may be combined further into roving as is a customary practice in the reinforcing fiber art.

The present roving may be utilized for any of the purposes to which reinforcing fibers are applied in the reinforced plastic arts, i.e., in winding tapes, in preform mats, as fibrous reinforcing substances and the like.

Preferably, as indicated schematically in FIGURE 2, strand or strands 18 are unwound from a spool 19 and passed into a chopping device 20. A stream of air is introduced into the chopping device 20 through a conduit 21 to provide a carrying stream 22 for chopped fiber lengths which may be directed against a foraminous preform surface or screen 23 having a configuration corresponding to the desired laminated article. The preform screen 23 preferably has mounted behind it an exhaust fan 24 to draw air continuously through the screen in order to maintain the short length of fibers in a random orientation on the exposed surface.

The chopped fiber lengths from the stream 22 form a preform mat 25 on the exposed surface of the preform screen 23. After the preform mat 25 has achieved the desired thickness, the stream 22 is interrupted and the preform mat is set, i.e., the individual fiber lengths are retained in the random orientation which they have assumed. This may be accomplished as in the past through the use of a spray of water-soluble adhesive, or, according to a preferred embodiment of this invention, by heating the preform mat 25 to a temperature which will fuse the resinous coating of the fibers, yet not initiate thermoset curing of the coating resins. A temperature of 100 to 250 F. should suflice. Conveniently the heating may be accomplished by passing steam of heated air through the preform mat 25 and the preform screen 23 for a brief period. A momentary blast of hot air or steam at 500 F., for example, might be sufiicient to cause the limited fusion which is desired without initiating the thermoset polymerization reactions.

The resulting fibrous-fused preform mat 25 then is withdrawn from the preform screen 23 and stored or transported to a laminating mold apparatus. Such molding devices are schematically illustrated in FIGURES 4 and 5 wherein a base mold element 26 and an upper mold element 27 are provided. The two elements 26, 27 can be mated to provide a mold cavity 28 therebetween. A preform mat 29 is deposited on the base mold element 26 within the mold cavity 28, as seen in FIGURE 3. Thereafter the upper mold element 27 is mated with the base mold element 26.to compress the preform mat 29 into the precise mold cavity 28. The mold elements 26, 27 are heated to cause curing of the thermosetting resinous materials which comprise the coating of the inindividual fibers of the preform mat 29. The resulting laminated article is withdrawn from the mold cavity after the mold elements 26, 27 are separated.

A specific example of the present invention will now be described.

The coacting resin mixture contains:

One part by weight of the reaction product of glycidyl methacrylate and Bisphenol A and three parts by weight of propylene meleate, the unsaturated polyester which is obtained by reacting propylene glycol with maleic anhydride. The diester polyether had the formula The resulting mixture is a solid substance at room temperature. The mixture is soluble in acetone.

Coating solution containing from 10 to 30 percent acetone by weight and the balance the 3:1 resin mixture were prepared. The solution also contained a small quantity (1 percent by weight of the resin) of toluhydroquinone as inhibitor and a small quantity (1 percent by weight of the resin) by benzoyl peroxide as polymerization initiator.

Glass fibers are passed through the resin bath and coated with the resin. The actone solventis fllashed from the coated fibers and the dry fibers are collected for use.

was readily varied according to the quantity of acetone in the solvent bath. It was also possible to utilize inert filler substances to regulate the viscosity of the bath and hence the amount of resin which adhered to the fibers as a coating.

Short lengths of the fibers were formed into a preform mat which contained fifty percent by weight glass fibers and fifty percent by weight of the described dry resin co ating.

The preform was compressed between two molding elements which were heated. The cured laminated article possessed excellent properties.

Because of the use of the present diester polyether in the resin formulation, the laminated article possessed remarkable heat distortion properties and high temperature strength retention. During the cure of the present preform mats, the initial application of heat within the molding apparatus causes fusion of the resin which allows the material to flow into the interstices of the compressed fibrous preform mat.

GENERAL The unsaturated polyesters which are incorporated into the present resin formulation are the reaction products of a glycol and an alpha-beta ethylenically unsaturated dicarboxylic acid or anhydride. Suitable glycol include: ethylene glycol, propylene glycol, diethylene glycol, clipropylene glycol, butylene glycol, octylene glycol, xylylene glycol, and the like. Suitable unsaturated dicarboxylic acids include maleic, fumaric, itaconic, citraconic, endomethylene tetrahydrophthalic, inter alia.

- In the formulation of the unsaturated polyester resins,

some saturated dicarboxylic acids and anhydride may be utilized for desired properties of the final product. Suitable saturated dicarboxylic acids which may be used include phthalic, isophthalic, terephthalic, and the like.

While the use of glass fibers is preferred because of their strength and convenience, other fibrous materials may be utilized in this invention, e.g., synthetic plastic fibers, natural fibers such as cotton, and the like. The resin mixture bath may have suitable fillers incorporated so that the resulting coated fibers will possess the desired properties which derive from the selected fillers.

In a further embodiment of the invention, the individual fibers or strands of fibers may be preliminarily coated with a thermoset resinous composition prior to application of the coating of this invention. For example, glass fibers or bundles of glass fibers may be coated with a conventional unsaturated polyester resin solution which is thereafter cured to a thermoset condition, thereby stiffening the relatively flexible fibers. By selecting the unsaturated polyester resinous composition of the desired hardness, the flexibility of the coated fibers may be regulated. The coated fibers with the thermoset resinous composition thereafter are coated according to this invention with dry, thermosetting resinous composition. A real advantage of utilizing such precoated fibers is that it permits the use of relatively inexpensive resins for controlling the stiffness of the fibers and minimizes the quantity of more costly resins which are utilized to complete the eventual laminated article.

The precoated fibers are also of especial interest in eliminating inherent weaknesses of the so-called weld lines which exist where multiple charges of fibrous material are introduced into a molding cavity. Customan'ly Where multiple charges are employed, the relatively soft and flexible fibers do not become intermeshed where the two charges adjoin through compression-instead the flexible fibers have a tendency to bend so that there is The ratio of weight of coating to weight of glass fibers little, if any, intermeshing of the fibers between the ad joining charges. As a result there has been observed inherent weakness along the so-called weld line between the adjoining charges. The stifiened, coated fibers of this invention promote intermeshing of the fibers and elimination of the so-called weld lines.

Where resinous mixtures are employed, the precise ratio of the unsaturated polyester resin to the diester poly- I claim: 1. Fibrous roving comprising discrete fibers each coated with a dry, thermosetting resinous mixture comprising: (a) an unsaturated polyester resin having alpha-beta ethylenic unsaturation; and (b) a polymerizable diester polyether resin having the formula ether is determined according to the chain length of each ingredient, according to the need for dryness in the solvent free mixture and according to the desired properties of the resulting laminated article. The diester polyether may comprise from about 10 to 100 percent of the resinous composition, preferably from about 20 to 50 percent.

wherein R is selected from the class consisting of hydrogen, lower aliphatic hydrocarbon radicals and phenyl radicals; and n is an integer from zero to twelve.

2. The method of preparing a dry, resin-coated fibrous Other specific diester polyethers which may be com- 25 material which comprises:

bined into the resinous mixtures include:

r passing individual fibers through a resinous bath conl C uHa 0 (A) and (D) may be prepared by reacting an epoxy resin (n:0)

O O 0112:0930 CHzCHCHzOCO CHzCHCHzO C=CH2 H l (in e taining a solvent anda normally solid thermosetting polymerizable resinous mixture comprising:

ll cup-no o omcnomo- @o (i R OE (a) an unsaturated polyester resin having alphabeta ethylenic unsaturation; and Y (b) apolymerizable resin having the formula v i 10 wherein R is selected from the class consisting resin-coated glass fibers secured with respect to one of hydrogen, lower aliphatic, hydrocarbon radianother through fusion of the said coating at points cals and phenyl radicals; and n is an integer of fiber-to-fiber t t, from zero to twelve; v 6. The method of making a laminated fibrous reinforced whereby said fibers become individually coated with plastic article which comprises introducing intoalaminatthe resinous mixture and solvent, ing mold a randomly oriented fibrous reinforcing mat comevaporating the solvent from the coated fibers to proprised of glass fibers coated with a dry, thermosetting duce substantially dry fibers and individually coated resinous mixture comprising: with the saidresinous mixture, (a) an unsaturated polyester resin having alpha-beta and recoveringthe dry, coated fibers into a strand of ethylenic unsaturation; and

discrete fibers. (b) a polymerizable resin having the formula v r O l H t om=eo oonrenonrooocmenomoooomonorno i o=cn, R on l 011 I on I HI)! 3): R

3. Afibrous reinforcing mat. preform for use in formwherein R is selected from the class consisting of hydromg laminated-articles comprising; l gen, lower aliphatic hydrocarbon radicals and phenyl lengths of fibers randomly oriented in av preform mat, radicals; and n is an integer from zero to twelve;

each filament being individually coated with a dry, compressing the said mat in the absence of additional therrnosetting resinous mixturecomprising: liquid monomers and heating the said dry mat to a (a) an unsaturated polyester resin having alphacuring temperature for thermosetting of the said beta; ethylenic unsaturation; and V, resinous coating, and recovering from the said lami- (b) a polymerizable resin having the formula nating mold a laminated article.

I I f o o-rn:eooc1'1iEHoH5o ooomgn0mo-keoomencmoiio=orn "whereinRisselectedfrom the class consisting 7. Fibrous roving comprising discrete filaments each of hydrogen, lower aliphatic,hydrocarbon radiv coated with a dry, thermosetting resinous normally solid cals and phenyl radicals; and composition comprising a polymerizable resin having the n is an integer from zero to t-welveL'. l following formula:

c a o capedoornoncnlo tgcocmcnomo-lnooomouomobc=om R "on on I 11 1'1 H1): (CH1):

4. The fibrous reinforcing mat of claim 3 wherein the wherein R is selected from the class consisting of hydroindividual fibers are secured in a random orientation by gen, lower aliphatic hydrocarbon radicals and phenyl e s o fusion Said 'y resin coating at Points radicals; and n is an integer from zero to twelve. fg gffi t 1 2: 3 o d d l o olfastge siarigofigirs. re 8. Coated fibrous roving comprising discrete fibers each {0 mzt 3 3 i z gi laamginategearticles i 5 coated with a dry, normally solid copolymerizable mixture c02 rises r n g comprising at least two thermosetting resinous ingredients P each having alpha-beta-ethylenic unsaturation, the said chopping continuous strands of coated glass fibers into short lengths, the said glass fibers being individually coated with a dry, thermosetting resinous mixture fibers comprising from 20 to 80 percent by weight of the coated roving.

9. A fibrous reinforcing preform mat for use in forming comprising:

(a) an unsaturated polyester resin having alpha- Laminated amcles Compflslngi beta ethylenic unsaturation; and lengths of coated fibers randomly oriented in the pre- (b) a polymerizable resin having the formula form mat, each fiber being individually coated with a l t CH= |3 OCH1CHCHzO-l00CHzCHCHO-h-COCH(EHCHOCSJ=CH1 R 61; I (in i OH R (CH3): Ha):

wherein R is selected from the class consisting dry, normally solid copolymerizable mixture comof hydrogen, lower aliphatic hydrocarbon radiprising at least two thermosetting resinous ingredients cals and phenyl radicals; and n is an integer each having alpha-beta-ethylenic unsaturation, the from zero to twelve; said fibers comprising from 20 to 80 percent by weight depositing the said lengths of coated glass fibers on a 65 of the coated fibers,

foraminous preform surface in a random orientation whereln the mdlvidual fibers are secured in a random to form a glass fiber preform mat conforming to the or entatlonby means of a fLlSlOll of the said copolymshape of the aid preform rfa e, nd heating th erizable mixture at points of fiber-to-fiber contact.

aid preform mat whil in t t ith th i re- 10. The method of preparing a dry, resin-coated fibrous form surface to fuse the said coating in those areas mateflal Whlch compflsesi where the said fibers are in contact with one another, P individual fibars through a Kesinolls bfllh Containwithout curing the said coating to a thermoset mg a solvent a pp y l xtur f t condition, least two normally SOlld thermosetting resinous suband recovering from the id preform surface a stances, each possessing alpha-beta-ethylenrc unsaturaform mat containing randomly oriented lengths of tion,

1 1 whereby said fibers become individually coated with the copolymerizable mixture and solvent; evaporating the solvent from the coated fibers to produce substantially dry fibers individually coated with the said copolymerizable mixture, and recovering the dry, coated fibers into a strand of discrete fibers, wherein the said fibers comprise from 20 to 80 percent of the weight of the strand. 11. The method of making a laminated fibrous reinforced the said preform surface and heating the said preform mat while in contact with the said preform surface to fuse the said coating in those areas where the'said fibers are in contact with one another, without curing the said coating to a thermoset condition.

13. The method of preparing a fibrous reinforced plastic article which comprises introducing into a laminating mold randomly oriented fibers coated with a dry, thermosetting resinous'composition comprising a polymerizable plastic article which comprises introducing into a laminatresin having the following formula:

I R OH ing mold a randomly oriented fibrous reinforcing preform mat comprised of glass fibers coated with a dry, thermosetting resinous mixture comprising at least two normally solid ingredients each having alpha-beta ethylenic unsaturation:

compressing the said preform mat in the absence of additional liquid monomers and heating the said dry preform mat to a curing temperature for the thermosetting of the said resinous coating, and recovering from the said laminating mold a laminated article. 12. The method of preparing a fibrous reinforcing preform mat for use in forming laminated articles which comprises:

chopping continuous strands of coated fibers into short lengths, the said fibers being individually coated with a dry, thermosetting resinous mixture comprising at least two normally solid copolymerizable ingredients each having alpha-beta ethylenic unsaturation, depositing the said lengths of coated fibers on a foraminous preform surface in a random orientation to form a fibrous preform mat conforming to the shape of o o ll cuppdoomonommoo cmorromon-ooomcrromoco=cm i on l. l on R z): wherein R is selected from the class consisting of hydrogen, lower aliphatic hydrocarbon radicals and phenyl radicals; and n is an integer from zero to twelve, the said article consisting essentially of the said fibers and the said resinous composition. 1

- References Cited UNITED STATES PATENTS 2,702,261 2/1955 Bacon et al. 161-168 2,860,687 11/1958 Cole 156-377 X 3,177,275 4/1965 Brenner 264-128 3,240,658 3/1966 Tucker t a1 161-170 3,256,226 6/ 1966 Fekete et a1. 260-861 3,030,247 4/1962 Schurb 161 3,276,945 10/1966 Frickert 161-175 EARL M. BERGERT, Primary Examiner.

T. R. SAVOIE, Assistant Examiner.

US. Cl. X.R.

Patent No. 3 ,428 ,518 February 18 1969 Kenneth A. Schafer pears in the above identified It is certified that error ap hereby corrected as patent and that said Letters Patent are shown below:

Columns 1 and 2, shown below:

cncn o- @FQOCH HCH OH-QQQocn utn OH H I lines 50 to 55 the formula should appear as Column 3, line 49, "thermostat" should read thermoset Column 5 line 2 before "fibrous" insert bulk line 55 "meleate" should read maleate line 70 "by" should read of Column 6 line 26 "glycol" should read glycols line 33, "anhydrlde" should read anhydrides Columns 7 and 8 formula (D) should appear as shown below:

0 O l l CH =COCH CHCH O C G OCH C|IHCH OLC=CH (QH l OH 1 Signed and sealed this 24th day of March 1970 (SEAL) Attest:

WILLIAM E. SCHUYLBR, JR.

EDWARD M.FLETCHER,JR.

Commissioner of Patents Attesting Officer 

1. FIBROUS ROVING COMPRISING DISCRETE FIBERS EACH COATED WITH A DRY, THERMOSETTING RESINOUS MIXTURE COMPRISING: (A) AN UNSATURATED POLYESTER RESIN HAVING ALPHA-BETA EHTYLENIC UNSATURATION; AND (B) A POLYMERIZABLE DIESTER POLYETHER RESIN HAVING THE FORMULA CH2=C(-R)-COO-CH2-CH(-OH)-CH2-O-((1,4-PHENYLENE)-C(-CH3)2(1,4-PHENYLENE)-O -CH2-CH(-OH)-CH2-O)N-(1,4-PHENYLENE)C(-CH3)2-(1,4-PHENYLENE)-O-CH2-CH(-OH) -CH2-OOC-C(-R)=CH2 WHEREIN R IS SELECTED FROM THE CLASS CONSISTING OF HYDROGEN, LOWER ALIPHATIC HYDROCARBON RADICALS AND PHENYL RADICALS; AND N IS AN INTEGER FROM ZERO TO TWELVE. 